1. Field of the Invention
The present invention relates to a light-emitting material (i.e., a light-emitting device material) and light-emitting device capable of converting electric energy to light which is then emitted and more particularly to a light-emitting device which can be preferably used in various arts such as display device, display, backlight, electrophotography, illuminating light source, recording light source, exposure light source, reading light source, sign, advertising display and interior. The present invention also relates to a novel light-emitting material which can be expected to find application in various arts.
2. Description of the Related Art
Today, various display devices have been under active study and development. In particular, an organic electric field light-emitting (EL) device can emit with a high luminance at a low voltage and thus has been noted as a favorable display device. For example, a light-emitting device having a vacuum-deposited thin organic layer has been known (Applied Physics Letters, vol. 51, page 913, 1987). The light-emitting device described in this reference comprises as an electron-transporting material tris(8-hydroxyquinolinate) aluminum complex (Alq) which is laminated with a positive hole-transporting material (amine compound) to exhibit drastically improved light-emitting properties as compared with the conventional single-layer type devices.
In recent years, the application of organic EL device to color display has been under active study. However, in order to develop a high performance color display, it is necessary that the properties of blue, green and red light-emitting devices be each improved.
As a means for improving the properties of light-emitting devices there has been reported a green light-emitting device utilizing the emission of light from orthometalated iridium complex (Ir(ppy)3: Tris-Ortho-Metalated Complex of Iridium (III) with 2-Phenylpyridine) (Applied Physics Letters 75, 4 (1999)). The foregoing device can attain an external quantum yield of 8%, which is higher than the limit of the external quantum yield of the conventional light-emitting devices, i.e., 5%. However, since the foregoing light-emitting device is limited to green light-emitting device, the range within it can be applied as a display is narrow. It has thus been desired to develop light-emitting materials capable of emitting light having other colors.
Noting a red light-emitting device, many light-emitting devices comprising DCM(4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran) and its analogy have been reported. No devices having an external quantum efficiency of more than 5% have been reported. If the external quantum efficiency of 5%, which is considered to be the limit of the external efficiency of the conventional red light-emitting device, can be surpassed, the development of high efficiency organic EL devices capable of emitting light having various colors can make a great progress. It has thus been desired to develop such high efficiency organic EL devices.
On the other hand, an organic light-emitting device which can attain light emission with a high luminance is one having a laminate of vacuum-deposited organic material layers. The preparation of such a device is preferably accomplished by a coating method from the standpoint of simplification of production procedure, workability, area attained, etc. However, the device prepared by the conventional coating method is inferior to that prepared by vacuum evaporation method particularly in light-emitting efficiency. It has thus been desired to develop a novel light-emitting material.
In recent years, various materials having fluorescence have been used in various arts such as filter dye, color conversion filter, dye for photographic material, sensitizing dye, dye for dyeing pulp, laser dye, fluorescent medicine for medical diagnosis and organic light-emitting material. Thus, there is a growing demand for such a material. New light-emitting materials have been desired.
An object of the present invention is to provide a light-emitting device having good light-emitting properties, a light-emitting material which can form such a light-emitting device, and a novel light-emitting material which can be used in various fields. (a first embodiment)
Another object of the present invention is to provide a red light-emitting device having good light-emitting properties, a light-emitting material which can form such a light-emitting device, and a novel light-emitting material which can be used in various fields. (a second embodiment)
The foregoing object of the invention can be accomplished by the following means.
1. A light-emitting material comprising a compound having a partial structure represented by the following formulae (1) to (10), (21), (22), or tautomer thereof: 
wherein R1 and R2 each represent a substituent; and q1 and q2 each represent an integer of from 0 to 4, with the proviso that the sum of q1 and q2 is 1 or more, 
wherein Z11 and Z12 each represent a nonmetallic atom group required to form a 5- or 6-membered ring with at least one of carbon atom and nitrogen atom, said ring optionally having a substituent or forming a condensed ring with the other ring; Ln1 represents a divalent group; Y1 represents a nitrogen atom or carbon atom; and b1 represents a single bond or double bond,
(CO)Irxe2x80x83xe2x80x83(5)
(NC)Irxe2x80x83xe2x80x83(6) 
wherein Z21 and Z22 each represent a nonmetallic atom group required to form a 5- or 6-membered ring with at least one of carbon atom and nitrogen atom, said ring optionally having a substituent or forming a condensed ring with the other ring; Y2 represents a nitrogen atom or carbon atom; and b2 represents a single bond or double bond, 
wherein X201, X202, X203 and X204 each represent a nitrogen atom or Cxe2x80x94R and forms a nitrogen-containing heteroaryl 6-membered ring with xe2x80x94Cxe2x95x90Nxe2x80x94, with the proviso that at least one of X201, X202, X203 and X204 represents a nitrogen atom; R represents a hydrogen atom or substituent; and Z201 represents an atomic group for forming an aryl or heteroaryl ring, 
wherein Z201 and Z301 each represent an atomic group for forming an aryl or heteroaryl ring, 
wherein Z201 and Z401 each represent an atomic group for forming an aryl or heteroaryl ring, 
wherein Z1 represents an atomic group which forms a heteroaryl ring.
2. The light-emitting material according to item 1, which comprises the compound represented by the formula (21) or (22), wherein said quinoline derivative ligand is formed by at least four rings.
3. A compound having a partial structure represented by the following formula (4) or a tautomer thereof: 
wherein Z11 and Z12 each represent a nonmetallic atom group required to form a 5- or 6-membered ring with carbon atom and/or nitrogen atom, said ring optionally having a substituent or forming a condensed ring with the other ring; Ln1 represents a divalent group; Y1 represents a nitrogen atom or carbon atom; and b1 represents a single bond or double bond.
4. A compound represented by the following formula (23) or (24): 
wherein R11 and R12 each represent a substituent; R13, R14 and R15 each represent a hydrogen atom or substituent; m1 represents an integer of from 0 to 4; and m2 represents an integer of from 0 to 6, 
wherein R11 and R12 each represent a substituent; m1 represents an integer of from 0 to 4; m2 represents an integer of from 0 to 6; Z2 represents an atomic group which forms an aryl or heteroaryl ring; Z3 represents an atomic group which forms a nitrogen-containing heteroaryl ring; and n1 represents an integer of from 1 to 3.
5. An organic light-emitting device comprising a light-emitting layer or a plurality of thin organic compound layers containing a light-emitting layer formed interposed between a pair of electrodes, wherein at least one layer comprises a light-emitting material having a partial structure represented by the following formula (1) to (10), (21), (22) or a tautomer thereof: 
wherein R1 and R2 each represent a substituent; and q1 and q2 each represent an integer of from 0 to 4, with the proviso that the sum of q1 and q2 is 1 or more, 
wherein Z11 and Z12 each represent a nonmetallic atom group required to form a 5- or 6-membered ring with at least one of carbon atom and nitrogen atom, said ring optionally having a substituent or forming a condensed ring with the other ring; Ln1 represents a divalent group; Y1 represents a nitrogen atom or carbon atom; and b1 represents a single bond or double bond,
(CO)Irxe2x80x83xe2x80x83(5)
(NC)Irxe2x80x83xe2x80x83(6) 
wherein Z21 and Z22 each represent a nonmetallic atom group required to form a 5- or 6-membered ring with at least one of carbon atom and nitrogen atom, said ring optionally having a substituent or forming a condensed ring with the other ring; Y2 represents a nitrogen atom or carbon atom; and b2 represents a single bond or double bond, 
wherein X201, X202, X203 and X204 each represent a nitrogen atom or Cxe2x80x94R and forms a nitrogen-containing heteroaryl 6-membered ring with xe2x80x94Cxe2x95x90Nxe2x80x94, with the proviso that at least one of X201, X202, X203 and X204 represents a nitrogen atom; R represents a hydrogen atom or substituent; and Z201 represents an atomic group for forming an aryl or heteroaryl ring, 
wherein Z201 and Z301 each represent an atomic group for forming an aryl or heteroaryl ring, 
wherein Z201 and Z401 each represent an atomic group for forming an aryl or heteroaryl ring, 
wherein Z1 represents an atomic group which forms a heteroaryl ring.
6. An organic light-emitting device according to item 5, wherein at least one layer consists essentially of the light-emitting material.
7. The light-emitting device according to item 5, wherein said layer comprising the light-emitting material is formed by a coating process.
8. An organic light-emitting device comprising a light-emitting layer or a plurality of thin organic compound layers containing a light-emitting layer formed interposed between a pair of electrodes, wherein at least one layer contains an orthometalated iridium complex, and said layer containing an orthometalated iridium complex is formed by a coating process.
9. An organic light-emitting device having an external quantum efficiency of 5% or more, and a xcexmax of light emitting of 590 nm or more.